Among the sources of protein occurring naturally are milk and soybeans, both of which are quite abundant and readily processed to obtain useful proteins for human consumption.
However, one of the serious drawbacks to the use of these natural proteins, particularly in food products, is the objectionable odor and offensive taste which militate against the use of these proteins at any reasonable levels due to the aforesaid organoleptic problems. Because of these organoleptic problems, only limited use of these proteins has been possible in the food industry.
As is well known, milk protein is comprised of caseins and whey proteins. Whey is the serum remaining after removal of fat and casein from milk, the whey proteins including lactalbumin as well as lactoglobulin and other proteins. The component proteins are separated from the whey protein by known methods. The soybean proteins are obtainable from the residues produced after removal of soybean oil from soybeans. The protein is characterized by a beany flavor which limits its use thereof. Many attempts have been made to improve the organoleptic properties of these natural proteins including denaturation, ion-exchange treatment, the use of salt additives and high-shear treatment but these have been found wanting.
Whey proteins have been subjected to denaturation and centrifugation or ultra-filtration as described, for example, in U.K. Specification No. 2,020,667; ultra-filtration to concentrate whey solutions as described in U.S. Pat. No. 3,896,241; and subjecting whey protein to blending shear forces in the presence of a metal gluconate salt at a temperature below the denaturation temperatures of the whey proteins, as described in U.S. Pat. No. 4,235,937. In U.S. Pat. No. 4,218,490 there is disclosed a process for making a foodstuff employing a proteinaceous additive derived from a variety of sources including soy, blood, whey and oil seeds by ion-exchange treatment and spray drying techniques. Soluble whey lactalbumen employed in the additive is only at low levels. U.S. Pat. No. 4,734,287 describes a proteinaceous, water-dispersible colloid composed of non-aggregated particles of sweet whey protein having a dry means particle size of from about 0.1 to about 2.0 microns which is prepared by subjecting undenatured whey protein or concentrates thereof to a high shear treatment in an aqueous medium at a highly acid pH in the presence of aggregate blocking agents. The product, when hydrated is indicated to have desirable organoleptic properties normally attributable to fat/water emulsions.
U.S. Pat. No. 4,918,008 is directed to a process of hydrolyzing proteins, including lactalbumin, to produce products which are useful for pharmaceutical products. The process involves treating the selected protein with a protease, optionally in the presence of a lipase only if the starting material contains appreciable amounts of fat.
Milk or cheese whey protein, including the component proteins of whey protein, are known to contain significant amounts of fat which cannot be removed by simple solvent extraction, suggesting that the fat is somehow bound to the protein. The off-taste and objectionable odor of whey protein is presumably attributed to deterioration of the fat molecules, for example, by oxidation of ethylenic bonds in the unsaturated fatty acid chain of the fat molecule. Protein containing soybean fiber also contains similar contaminants which are responsible for the objectionable off-taste.
While the aforesaid prior art processes can result in whey protein products of reasonable organoleptic properties, these products develop off-taste and objectionable odors in relatively short periods of time on storage. In a matter of a few days, they can develop these undesirable properties which render them unfit for commercial use as, for example, human protein supplement or other use in foods intended for human consumption.
In contrast, the present process yields bland, odor-free natural protein which remains bland and odor-free over protracted periods of dry storage, for at least periods of 3 months and for up to 6 months and even one year and longer.